Dressing device for grinding wheels



April 1,1944. J. WELSAND, JR, El'AL ,3

DRESSING DEVICE FOR GRINDING WHEELS Filed June 5, 1942 5 Sheets-Sheet 1 fie. 2

INVENTORS JbH/Y WELSH/Y0 .77: BY 40m LEJL/E LE5 ATTORNEYS April 1944. J. WELSAND, JR., EIAL ,346, 2

bRESSINQr DEVICE FOR GRINDING WHEELS Fiied June 5, 1942 5 Sheets-Sheet 2 l I I u l l l 1 INVENTORS JEw/v Wszsmvo]? BY lam 0 ZESL/E LEE April 11, 1944, J. WELSAND, JR, r AL 2,346,523

- DRESSING DEVICE FOR GRINDING WHEELS Filed June 5, 1942 5 Sheets-Sheet 5 4 I Q j {is I g I ll .2 l 5 HI M .llllll W2 3 \l x V Q M). g

l INVENTORS J5HH Was/wows BY (Arno 4554/5. LEE

MZ W rfflz ATTORNEYS April 11, 1944. J. WELSAND, JR, ETAL 2,346,528

DRESSING DEViCE FOR GRINDING- WHEELS Filed June 5; 1942 s Shets-Sheet 4 INVENTORS JbH/v WELAA/D J2.

ATTORNEY 5 g N M J. WELEAND, JR, ET AL.

DRESSING DEVICE FOR GRINDING WHEELS- 5 Sheets-Sheet 5 Filed June 5, 1942 w s GEE M V D L W mw of AM i 5/. .3 W; -my o 5m f w Patented Apr. 11, 19 44 nanssme nnvrcn For. Gamma WHEELS John Welsand, Jr., and Lloyd Leslie Lee, Detroit,

Mich., assignors to Eaton Manufacturing Company, Cleveland, Ohio, a corporation of Ohio Application June 5, 1942, Serial No. 445,868

12 Claims.

The present invention relates to grinding machines for grinding the inner member of a motor or pump comprising an outer internal gear-like member having a plurality of helical threads or teeth, the profile or form of which is preferably a circle, and an inner external gear-like member within the first member and having one less thread or tooth than the outer member, the form or profile of which is generated from-the outer rotor and is such as to form with the outer member chambers which contract and expand upon relative rotation of the members.

More particularly the present invention relates to means for dressing a grinding wheel used for V grinding the inner member of a device of the character referred to.

The invention resides in certain details of construction and combinations and arrangements of parts andfurther objects and advantages thereof will be apparent to those skilled in the art to which the invention relates from the following description of the preferred embodiment described with reference to the accompanying Fig. 2 is a diagrammatic view showing the principal movements of a dressing device for a grinding wheel, which dressing device embodies the present invention;

Fig. 3 is an end view of a dressing device for a grinding machine, which dressing device embodies the movements shown in Fig. 2;

Fig. 4 is a sectional view, with portions in elevation, approximately on the line ll of Fig. 3; Fig. 5 is an end view of the device shown in Fig. 4, looking from the right, with the grinding wheel omitted;

Fig. 6 is a section, with portions in elevation, approximately on the line 6-6 of Fig. 3;

Fig. 7 isa section on the line l-I of Fig. 4; Fig. 8 is a section on-the line 88,of Fig. 4; Fig. 9 is an enlarged section approximately on the line 99 of Fig. 3: and g i Fig. 10' is a section approximately on the line lO-Hl of Fig. 9. Referring to the drawings, Fig. 1 shows two members A and B of a pump on-the order of the pumps shown in U. S. patent to Myron F. Hill. No. 1,862,563 issued August 28, 1928, disposed Fig. 2, connecting the center 7' of the profile one within the other. As illustrated outer member A has five internal teeth 10, the profile of which is an arc of a circle 1, the center of which is atj, and the radius of which is r, referring to the upper tooth as viewed in Fig. 1. The inner member 3 has four external helical teeth It conjugate to the teeth of the outer member A. As previously stated, the inner memberor rotor 'usually has one less tooth than the outer member or rotor. Applyin the principle that when uniform rotary motion is transmitted by means similar to gear teeth, the normals to the profiles at all points of contact pass through the point of contact of their pitch circles, the form of the inner rotor B is generated by the intersection of the profile circle i and a line i, k, see

circle 1' and the point of contact is of the respective pitch circles l and 112.

According to the provisions of the present invention, a diamond or some similar dressing point for a grinding wheel is caused to travel the path traced by the intersection-n of the'profile curve t and a line :I, in connecting the center of the profile circle i and the point of contact k between the outer rotor pitch circle I and the inner. rotor pitch circlem, v thus dressing the grinding wheel to the desired form. For mechanical reasons the pump is usually constructed in such a manner that in operation the inner rotor B gyrates with reference to the outer rotor A but for present purposes it is assumed, for reasons which will be hereinafter more apparent, that the outer rotor A gyrates with reference to the inner rotor B rotating in a counterclockwise direction around the stationary inner rotor B.

Fig. 2 shows the relative positions'of the respective pitch circles, the profile circle 1', and the centersthereof after the point of contact k between the outer rotor pitch circle and the inner rotor pitch circle has traveled Assuming that at the beginning the partswere inthe position shown in Fig. 1, this angle represents the travel of the line 7a,. 0 connecting the center 0 of the outer rotor pitch circle'l with the point of contact In between the pitch circles I and m about the center 11 of the inner rotor pitch circle m. The angle between the lines 1, o and k, 0 represents the relative rotation of the outer rotor A about its center 0 which center traces the circle a. The reference character 8 indicates the center of the jackshaft gear pitch circle thereinaftermore specifically referred to. a,

Referring to Fig. 4 of the drawings, the reference character C designates generally the frame left-hand end of which, as viewed in Fig. 4, is

adjustably secured by a clamp screw i3 in an angular hole M in a bracket IS. The bracket l5 is in turn fixed to the right-hand end of a. shaft l6 rotatably supported by anti-friction bearings l1 and II in a housing assembly, designated generally by the reference character E. The center line 1' of the shaft Iii corresponds with the center j of the profile circle i, see Figs. 1 and .2.

The angular relationship of the hole in the bracket l5 raises and lowers the diamond D relative to the center line a" of the shaft l6 as the diamond holder I2 is moved in or out of the hole l4. This adjustment provides means for setting the diamond D a distance below the center line 1' corresponding to the radius of the profile circle 1'. The diamond holder I2 is adapted to be secured in'any' adjusted position within the bracket l5 by the clamp screw l3. A bar shown in dotdash lines in Fig.4, the head 2i of which is made to the correct radius of the profile circle i, and is a half diameter, is preferably used for setting the diamond D in 'correct position. The shaft [6 has a coaxial aperture 22 therein adapted to receive the left-hand reduced end of the bar 20 and the half diameter line is kept in line with an'imaginary line in the dressing device correspondihg with the line 7', k of Figs. 1 and 2 by a key 24 carried by the bar 20 and adapted to engage in a suitable keyway 25 in the shaft l6 and bracket l5.

The housing assembly E comprises a member carried by a plate 3| keyed to the hub 32 of a gear 33, the pitch circle I of which corresponds with the outer rotor pitch circle I. The gear 33 is supported by bearings 34 and 35 for rotation about a center line 0' corresponding with the center of a shaft 36 keyed to a. carrier 31 rotatably supported in the stationary frame or housing C by anti-friction bearings 38 and 39 for rotation about a center line 12' corresponding with the center p, Figs. 1 and 2.. Fixedly keyed to the right-hand end of the shaft 36. as viewed in Fig. 4, is a crank arm or eccentric 40 provided with a plunger 4| having a V-shaped end 42 which'slidably engages in a V-shaped groove 43 in an arm '44 fixed to the left-hand end of the shaft l6. The plunger is rotatably supported in the crank arm 40 and the axis of rotation k thereof corresponds with the point it of Figs. 1 and 2 and corresponds with the point of contact between the pitch circle 1' of the gear 33 extended corresponding with the outer rotor pitch diameter! and the pitch circle m of a gear 45,.hereinafter more specifically referred to, which pitch circle m corresponds with the inner rotorpitch circle m. From the foregoing it will be apparent that the bottom of the V-shaped groove 43 in the arm 44 corresponds with the line 77a of Figs. 1 and 2 and that the diamond point D is ,in line therewith. .The gear 45 is formed integral with the right-hand end of a shaft-48 keyed to a plate 41 forming a part of the stationary housing C.

The carrier 31 is rotated about-its axis of rotation 9 by a gear II, the teeth of which are continuously in mesh with gear teeth 5| formed about the periphery of the carrier. The assem- 'bly'E, including the gear 33. is rotated about the shaft 36 in timed relation to the rotation of the carrier 31 by two jackshaft gears 82 and 33 formed integral with a jackshaft 54 supported in the carrier31 for rotation about a center line s' corresponding with the point s of Fig. 2. The pitch-circles t and t" of the gears 52 and i3 coincide and correspond with the pitch circle t of Fig.2. The gear 52 is continuously in mesh with the gear 45, the pitch circle m of which corresponds with the inner rotor pitch circle m. and the gear 53 is continuously in mesh with the gear 33, the pitch circle? of which corresponds with the outer rotor pitch circle I. In the embodiment of the invention shown, the jackshaft gears 52 and 53 are provided with conventional backlash eliminating mechanism 35 and 56. This mechanism per se forms no part of the present invention and will not be described in detail. Suflice it to say that any suitabie'backlash mechanism may be employed. As shown, the plate 3| is rotatably supported in the housing. C adjacent to its circumference by anti-friction bearings and 6| located on opposite sides of the plate. These bearings help to support the overhanging weight of the housing E and lessen the load to which the shaft 36 would be otherwise subjected.

Assuming that at the beginning of the dressing operation the parts are in the position shown in Figs. 3 and 4, the gear Ill and, in turn, the carrier 31 are rotated first in one direction to dress onehalf of the wheel and then in the opposite direction to dress the other half of the wheel. To dress either half of the wheel it is only necessary to rotate the carrier 300. As shown, when the carrier 31 is rotated in the counterclockwise direction, as viewed in Fig. 3, the left-hand half of the grinding wheel, as viewed in Fig. 8, is dressed-and, when the carrier 31 is rotated in the opposite direction, the right-hand half of the grinding wheel is dressed.

In the embodiment disclosed, the gear "50, through the medium of which the carrier 31 is oscillated, is keyed to a short shaft 32, see Fig. 6, rotatably supported in the housing C by antifriction bearings 63 and 64 and is adapted to be oscillated in the required manner by a reciproeating type fiuid pressure operated motor F comprising a piston 65 slidably supported in a cylinder 6B and connected by a piston rod 61 to a member 68 having rack teeth 69 formed integral therewith, which rack teeth are continuously in mesh with a gear 10 fixed to the shaft 62. e fiow of fluid pressure to and from the fluid pres- .sure motor may be accomplished in any convenient manner. It is preferably so constructed and connected with other operations of the grinding machine that the grinding wheel is automatically equally and uniformly periodically dressed.

In the embodiment of the invention shown a uniform feed of the diamond point across the arcuate face of the grinding wheel is attained. through the medium of a metering valve G which controls the supply or discharge of fluid from the fluid pressure motor F. As shown, the metering valve G is connected in the supply line but it is to be understood that it may be connected in the discharge line. The metering valve is connected to the fluid pressure motor F through a four-way reversing Valve H, which reversing valve is preferably automatically controlled from some moving part of the machine so as to automatically effect a periodic dressing of the grinding wheel.

The reversing valve H is of commercial construction and will not be described in detail.

Referring to Figs. 3, 9, and 10, the conduit I is connected to a source of fluidpressure and communicates with an orifice 16 in the metering valve G. The orifice l6 communicates with the interior of the valve G and an aperture 11 in the end of a slidable plunger 18. The flow of fluid from the orifice 16 to the aperture 11 and in turn to the conduit 80 leading to the reversing valve H is controlled or metered by the position of the plunger 18, the open end of which is closed or partially closed by the end of an adjustable pin II which provides means for adjusting the amount of fluid pressure which may be passed through the valve. The end of the plunger 18 opposite the aperture I1,- that is the left-hand end, as viewed in Figs. 9 and 10,.is provided with a roller 82 in engagement with a cam track 83 formed on the member 88. The contour of the cam track 83 is such as to compensate for the inherent characteristics of the movements em ployed in the dressing device which would normally cause the diamond point to travel across the arcuate face of the grinding wheel at a nonuniform rate. The reversing valve H isconnected to the fluid pressure motor F by the conduits 85 and 86. The discharge conduit is designated by the reference character 81.

While the invention has been herein illustrated and described as embodiedin adevice for dressing a grinding wheel for grinding a particular member of a pump of specific construction, it is to be understood that the invention is not limited to a dressing device for dressing the specific grinding wheel shown but is applicable to the dressing of grinding wheels suitable for grinding rotors of pumps similar to the pump referred to hereinbut of different construction, and while the preferred embodiment of the invention has been described with considerable detail, it will be apparent that the invention is not limited to the particular construction, shown which may be varied within the scope of this invention.

Having thus described ourinvention we claim: 1. A dressing device for a grinding wheel comprising: a housing a carrier rotatably supported by said housing for rotation about an axis; a

said shaft, means operatively connecting said carrier and said housing for rotating said housing in timed relation to the rotation of said carrier;

and a grinding wheel dressing tooloperatively connected to said shaft. I

2. A dressing device for a grinding wheel com- I prising: a stationary housing; a carrier rotatably supported by said housing for rotation about a. fixed axis; a movable housing supported by said carrier for rotation about an axis parallel with but offset from the axis of rotation of said carrier; a shaft rotatably supported in said movable housing for rotation about an axis parallel with but offset from the axis of rotation "of both said said shaft.

3. A dressing device for a grinding wheel comprisingz-a first gear; a carrier assembly comprising a jackshaft having a second and thirdgear fixed thereto; means for rotatably supporting said carrier assembly coaxially with the center of the first-named gear; a member including a fourth gear; means for rotatably supporting said member by said carrier for rotation about an axis parallel with but offset from the axis of rotation of said carrier; means for rotatably supporting. said jackshaft in said carrier assembly with its axis of rotation parallel with the axis of rotation of said carrier assembly and with said second and third gears in mesh with said first and fourth gears respectively; the pitch circles of said second and third ears when extended being coincident andthe points of contact of the pitch circles of said second and third gears with said first and fourth gears respectively lying on a line parallel with the axis of rotation of the second, third, and fourth gears; a shaft rotatably supported in said movable housing for rotation about an axis parallel with but offset from the axes of rotation of both said carrier assembly and said movable housing; said carrier assembly comprising a crank the center of which is in line with the points of contact between the pitch circles of said first and second gears and the pitch circles of the third andfourth gears and offset from the axis of rotation of said shaft;

4. A dressing device for a grinding wheel comprising: a stationary housing comprising a first gear; a carrier assembly comprising a jackshaft having a second and third gear fixed thereto: means for rotatably supporting said carrier assembly coaxially with the center of the firstnamed gear; a movable housing assembly including a fourth gear; means for rotatably supporting said movable housing assembly by said carrier for rotation about an axis parallel with but offset from the axis of rotation of said carrier; means for rotatably supporting said jackshaft in said carrier assembly with said second and third gears in mesh with said first and fourth gears respectively; the pitch circles of said second and carrier and said movable housing proper; a crank on said carrier; means for operatively connecting said crank and said shaft; means comprising planetary gearing operatively connected to said carrier and said housing for rotating said housing in timed relation to the rotation of said carrier; means for rotating said carrier; and a grindthird gears when extended being coincident and the points of contact of the pitch circles of said second and third gears with said first and fourth gears respectively lying on a line parallel with the axis of rotation of the second, third, and fourth gears; said movable housing assembly including a shaft rotatably supported therein for rotation about an axis parallel with but offset from the axis of rotation of said movable housing assembly proper; said carrier-assembly including a crank the center of which is in line with the points of contact between the pitch circles of said first and second gears and the pitch circles of the third and fourth gears and offset from the axis of rotation of said shaft; means for operatively connecting said crank and said shaft; a wheel dressing tool operatively carried by said shaft; and means for rotating said carrier assembly.

5. In a dressing device for producing a profile including a reverse curve the combination of: a member; a tool holder; means for pivotally supporting said tool holder in said member for oscillation about an axis offset from the profile to be produced and angulariy disposed to the plane thereof; said tool holder having a tool extending transversely of the axis of oscillation of the tool holder; means for moving said member in a plurality of directions in a plane at right angles to the axis of oscillation of said tool holder; and means for oscillating said tool holder about its pivotal axis simultaneously with and in predetermined relation to the movement of said member whereby the longitudinal axis of the tool is always maintained substantially normal to the profile being produced at its point of contact therewith.

6. In a dressing device for a grinding wheel having a profile including a reverse curve the combination of: a member; a tool holder in said member; means for pivotally supporting said tool holder for oscillation about an axis oflset radially outwardly from the grindingwheel and angularly disposed to its axis of rotation; said tool holder having a tool extending transversely of the axis.

of oscillation of the member; means for moving said member in a plurality of directions at right angles or normal to the axis of rotation of said tool holder; and means for oscillating said tool holder about its axis of oscillation simultaneously with and in pizzdetermined relation to the movement of said member whereby the longitudinal axis of the tool is always maintained substantially normal to the profile of the grinding wheel at its place of contact therewith.

'1. In a dressing device for a'grinding whee the combination of: a frame; a member; means for movably supporting said member in said frame for movement in a plurality of directions in one plane; a tool holder; means for pivotally supporting said tool holder in said member for oscillation about an axis perpendicular to the plane of movement of said member and offset from and angularly disposed to the axis of rotation of the grinding wheel; said tool holder having a tool extending radially of the axis of rotation thereof; means for moving said member in a pluralityof directions in its plane of movement; and means for oscillating said tool holder about its pivotal axis simultaneously with and in such predetermined relation to the movement of said member that the longitudinal axis of the tool is always maintained substantially normal to the profile of the grinding wheel at its place r of contact therewith.

8. In a dressing device for a grinding wheel the combination of a frame; an eccentric; meansfor rotatably supporting said eccentric; a member rotatably supported'on said eccentric; a tool holder; means for pivotally supporting said tool axis perpendicular to the plane or movement of said member and oifset'froin and angularly disposed to the axis of rotation of the grinding wheel; said tool holder having a tool extending transversely of the axis of rotation thereof; means for rotating said member and means for rotating v holder in said member for oscillation about an said eccentric in timed relation to the rotation of said member whereby said member is moved in a plurality of directions in its plane of movement and the tool is caused to traverse a path including a reverse curve; and means for oscillating said toolholder about its pivotal axis in predetermined relation to the movement of said member whereby supported in said frame; an eccentric fixed to said member; a second member rotatably supported on said eccentric; a. tool holder pivotally supported by said second member for oscillation about an axis parallel to but offset from the axis of rotation of said member and ofiset from and angularly disposed to the axis of rotation of the grinding wheel; said tool holder having a tool extending transversely of the axis oi rotation thereof; means for rotating said member and means for rotating said second member in timed relation to the rotation of said member whereby said axis of said tool carrier is moved in a plurality of directions in a plane normal thereto and caused to traverse a path including a reverse curve; and means including a second eccentric connected to said member for oscillating said tool holder about its pivotal axis whereby the longitudinal axis of the tool is always maintained substantially normal to the profile of the grinding wheel at its place of contact therewith.

10. In a dressing device for a grinding wheel employed to form grind the inner rotor of a mechanism of the character described the outer rotor of which has arcuate lobes or. teeth and the form of which inner rotor is generated from the outer rotor; the combination of a frame; a first gear fixed to said frame and having a pitch circle corresponding with the pitch circle of the inner rotor; a carrier assembly; means for rotatively supporting said carrier assembly relative to said frame coaxially with the center of said first gear; an eccentric on said carrier assembly the center of which corresponds with the center of the pitch circle of the outer rotor; a member tact said first and second gears respectively upon a line passing through the point of contact between the' pitch circles of said first and second gears and the inner and outer rotors; a shaft rotatively supported in said member for rotation about an axis offset from but parallel with the axis of said first and second gears and corresponding with the center of the profile circle of the teeth or lobes of the outer rotor; a second eccentric on said carrier assembly, the center of which eccentric is in line with the points of contact between the pitch circles of said first and third, and said second and fourth gears and corresponds with the point of contact between the pitch circles of the inner and outer rotors; an arm on said shaft, having a slot within which said second eccentric engages; a tool carried by said shaft, said tool having its longitudinal axis extending transversely of the axis of rotation of said shaft with the point of the tool extendin .towardg said axis but ofi'set therefrom an amount equal to the radius of the profile circle of the teeth or lobes of said outer rotor and corresponding with the intersection of the profile circle and a line connecting the center thereof and the point of contact of the pitch circles of the inner outer rotors; and means of producing a relative oscillation between said frame and said carrier assembly.

11. In a dressing device for a grinding wheel employed to form grind the inner rotor of a mechanism of the character described the outer rotor of which has arcuate lobes or teeth and the form of which inner rotor is generated from the outer rotor, the combination of: a frame; a first gear fixed to said frame and having a pitch circle cor- .responding with the pitch circle of the inner rotor; acarrier assembly; means for rotatively supporting said carrier assembly relative to said frame coaxially with the center of said first gear; an eccentric on said carrier assembly the center of which corresponds with the center of the pitch circle of the outer rotor; a member rotatively supported on said eccentric; a second gear fixed to said member and having .a pitch circle corre-' sponding with the pitch circle of said outer rotor and contacting the pitch circle of said first gear extended; a jack shaft; third and fourth gears fixed to said jack shaft; means for rotatively supporting said jack shaft in said carrier assembly so that the pitch circles of said third and fourth gears which are coincident contact said first and second gears respectively upon a line passing through the point of contact between the pitch circles of saidfirst and second gears and the inner and outer rotors; a shaft rotatively s pported in said member for rotation about an axis offset from but parallel with the axis of said first and second gears and corresponding with the center of theprofile circle of the teeth or lobes of the outer rotor; a second eccentric on said carrier assembly, the center of which eccentric is in line with the points of contact between the pitch circles of said first and third, and said second and fourth gears and corresponds with the point of contact between the pitch circles of the inner and outer rotors, an arm on said shaft having a slot within which said second eccentric engages; a tool carried by said shaft, said tool having its longitudinal axis extending transversely of the axis of rotation of said shaft with the point of said tool extending towards said axis but offset therefrom an amount equal to the radius of the profile circle of the teeth or lobes of said outer rotor and corresponding with the intersection of the profile circle and a line connecting the center thereof and the point of contact of the pitch circles of said first and second gears and the inner and outer rotors; and means of producing a relative oscillation between said frame and said carrier assembly at a variable speed such that the point of the tool traverses the profile of the grinding wheel at substantially uniform speed.

12. In a dressing device for a grinding wheel employed to form grind the inner rotor of a mechanism of the character described the outer rotor of which has arcuate lobes or teeth and the form of which inner rotor is generated from the outer rotor, the combination of a frame; a first gear fixed to said frame and having a pitch circle corresponding with the pitch circle of the inner rotor; a carrier assembly; means for rotatively supporting said carrier assembly relative to said frame coaxially with the center of said first gear;

an eccentric on said carrier assembly the center of which corresponds with the center of the pitch circle of the outer rotor; a member rotativel supported on said eccentric; a second gear fixed to said member and having a pitch circle corresponding with the pitch circle of said outer rotor and contacting the pitch circle of said first gear extended; a jack shaft; third and fourth gears fixed-to said jack shaft; means for rotatively supporting said jack shaft in said carrier assembly so that the pitch circles of said third and fourth gears which are coincident contact said first and second gears respectively upon a line passing through the point of contact between the pitch circles of said first and second gears and the inner and outer rotors; a shaft rotatively supported in said member for rotation about an axis offset from but parallel with the axis of said first and second gears and corresponding with the center of the profile circle of the teeth or lobes of the outer rotor; a second eccentric on said carrier assembly, the center of which eccentric is in line with th oints of contact between the pitch circles of said first and third, and said second and fourth gears and corresponds with the point of contact between the pitch circles of the inner and outer rotors, an arm on said shaft having a slot within which said second eccentric engages; a second member fixed to said shaft, said second member having an aperture therein offset from and angularly disposed with respect to the axis of said shaft; 9. tool holder adjustably secured in. said aperture in said second member; a tool carried by said tool holder, said tool having its longitudinal axis extending transversely of the axis of rotation 01' said shaft with the point of the tool extending towards said axis but ofiset therefrom an amount equal 'to the radius of the profile circle of the teeth or lobes of said outer rotor and corresponding with the intersection of the profile circle and a line connecting th center thereof and the point of contact of the pitch circles of said first and second gears and the inner and outer rotors; and means of producing a relative oscillation between said frame and said carrier assembly at a variable speed such that the point of the tool traverses the profile of the grinding wheel at substantially uniform speed.

- JOHN WELSAND, Jn. LLOYD nEsLm LEE. 

